Radio communication system, radio apparatus, radio communication method, packet generation method, and method for reproducing data from packet

ABSTRACT

A transmission unit of a radio apparatus generates a packet including: a header part containing identifier data identifying at least a transmission destination radio station and a transmission source radio station; and a data part in which an audio frame and a data frame, each having a predetermined length, are consecutively arranged one after another. When communication is performed in a fast data mode in which data for data communication to be transmitted, instead of a digital audio signal, is inserted in the audio frame, the transmission unit generates, according to an instruction from the controller, a packet in which data for data communication is inserted in the audio frame and the data frame, and the transmission unit converts the packet into a radio signal and transmits the radio signal.

CROSS REFERENCE TO RELATED APPLICATIONS

The disclosure of Japanese Patent Application serial No. 2015-30811,filed on Feb. 19, 2015, including the specification, drawings andabstract is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a radio communication system employingdigital audio communication, a radio apparatus used in the system, and aradio communication method, a packet data generation method, and amethod for reproducing data from a packet, that correspond to thesystem.

2. Description of the Related Art

In recent years, a digitized and networked environment for audiocommunication has been developing in the field of amateur radio forexample, so that the users can enjoy communication at higher speed andexchange clearer audio messages. In a radio communication systememploying such digital audio communication, audio signals are encodedand converted into digital signals, and are transmitted after beingpacketized (for example, see JP 2006-157477A).

In the aforementioned radio communication system, data indicating a callsign of the transmission destination, data indicating a call sign of thetransmission source, etc. are added to the header part of the packet,and accordingly the system can achieve many functions such as thefunction of performing communication with the designation of thecommunication party station, which cannot be achieved by analogue radiocommunication systems.

Furthermore, according to the aforementioned radio communication system,audio frames and data frames, each having a predetermined length, areconsecutively arranged one after the other, so that data for audiocommunication and data for data communication can be simultaneouslytransmitted.

Therefore, with use of this function, image signals captured by a cameracan be transmitted from one radio apparatus to another radio apparatusduring communication, so that the image is displayed on a display andthe users can enjoy a conversation while seeing the image, for example.

However, the aforementioned conventional radio communication system isdesigned for audio communication, and the amount of data that can betransmitted in data communication is set to be smaller than the amountof data that can be transmitted by audio communication, and thecommunication speed of the data communication is not necessarily high.Therefore, improvement has been demanded.

BRIEF SUMMARY OF THE INVENTION

The present invention is made in view of such a situation, and aims toprovide a radio communication system that can increase the communicationspeed of data communication.

A radio communication system according to the present invention is aradio communication system including at least two radio apparatuses,

each radio apparatus comprising:

a transmission unit configured to generate a packet including: a headerpart containing identifier data identifying at least a transmissiondestination radio station and a transmission source radio station; and adata part in which an audio frame and a data frame, each having apredetermined length, are consecutively arranged one after another, toinsert audio signal data into the audio frame of the packet and toinsert data other than the audio signal data into the data frame of thepacket, and to thereafter convert the packet into a radio signal andtransmit the radio signal;

a reception unit configured to receive the radio signal, to reproduce apacket from the radio signal, to retrieve the audio signal data from theaudio frame of the packet, and to retrieve the data other than the audiosignal data from the data frame of the packet;

an audio codec configured to generate a digital audio signal byperforming A/D conversion and encoding on an analogue audio signal andthereafter transmit the digital audio signal to the transmission unit,and to reproduce an analogue audio signal by performing decoding and D/Aconversion on a digital audio signal received from the reception unit;and

a controller configured to instruct the transmission unit to generate apacket, and to instruct the reception unit to reproduce a packet from areceived radio signal,

wherein, when communication is performed in a fast data mode in whichdata for data communication to be transmitted, instead of audio signaldata, is inserted in the audio frame,

the transmission unit of a radio apparatus serving as a sendergenerates, according to an instruction from the controller, a packet inwhich data for data communication is inserted in the audio frame and thedata frame, and information indicating that the data for datacommunication is inserted in the audio frame is further inserted in apredetermined position in the data frame, and

the controller of a radio apparatus serving as a recipient, which hasreceived a radio signal, analyzes the information inserted in thepredetermined position in the data frame of the packet reproduced by thereception unit, to determine that the data for data communication isinserted in the audio frame, and according to a result of thedetermination, retrieves data from the audio frame and the data frame ofthe packet and reproduces the data for data communication.

A radio apparatus according to the present invention is a radioapparatus comprising:

a transmission unit configured to generate a packet including: a headerpart containing identifier data identifying at least a transmissiondestination radio station and a transmission source radio station; and adata part in which an audio frame and a data frame, each having apredetermined length, are consecutively arranged one after another, toinsert audio signal data into the audio frame of the packet and toinsert data other than the audio signal data into the data frame of thepacket, and to thereafter convert the packet into a radio signal andtransmit the radio signal;

an audio codec configured to generate a digital audio signal byperforming A/D conversion and encoding on an analogue audio signal andthereafter transmit the digital audio signal to the transmission unit;and

a controller configured to instruct the transmission unit to generate apacket,

wherein, when communication is performed in a fast data mode in whichdata for data communication to be transmitted, instead of audio signaldata, is inserted in the audio frame,

the transmission unit generates, according to an instruction from thecontroller, a packet in which data for data communication is inserted inthe audio frame and the data frame, and information indicating that thedata for data communication is inserted in a predetermined position inthe audio frame is further inserted in the data frame.

A radio communication method according to the present invention is aradio communication method for a radio communication system including atleast two radio apparatuses, one of the at least two radio apparatusesbeing configured to generate a packet including: a header partcontaining identifier data identifying at least a transmissiondestination radio station and a transmission source radio station; and adata part in which an audio frame and a data frame, each having apredetermined length, are consecutively arranged one after another, andto convert the packet into a radio signal and transmit the radio signal,and another one of the at least two radio apparatuses being configuredto receive the radio signal and reproduce a packet from the receivedradio signal, the radio communication method comprising the steps of:

with a radio apparatus serving as a sender,

-   -   generating a packet in which data for data communication is        inserted in the audio frame and the data frame, and information        indicating that the data for data communication is inserted in        the audio frame is inserted in the data frame; and    -   converting the generated packet into a radio signal and        transmitting the radio signal, and

with a radio apparatus serving as a recipient,

-   -   receiving the radio signal;    -   reproducing a packet from the received radio signal;    -   analyzing information that is inserted in the data frame of the        reproduced packet to determine whether or not data for data        communication is inserted in the audio frame; and    -   when determining that the data for data communication is        inserted in the audio frame, retrieving data from the audio        frame and the data frame of the packet and reproducing the data        for data communication.

A packet generation method according to the present invention is apacket generation method for a radio apparatus that performscommunication with another radio apparatus by using a packet thatincludes: a header part containing identifier data identifying at leasta transmission destination radio station and a transmission source radiostation; and a data part in which an audio frame and a data frame, eachhaving a predetermined length, are consecutively arranged one afteranother, the packet generation method comprising the steps of:

inserting data for data communication into the audio frame and the dataframe; and

inserting, into the data frame, information indicating that the data fordata communication is inserted in the audio frame.

A method for reproducing data from a packet performed by a radioapparatus according to the present invention is a method for reproducingdata from a packet performed by a radio apparatus that is configured toreceive a radio signal containing a packet generated by theabove-described packet generation method, and to reproduce the packetfrom the radio signal, the method comprising the steps of:

analyzing information that is inserted in the data frame of thereproduced packet to determine whether or not data for datacommunication is inserted in the audio frame; and

when determining that the data for data communication is inserted in theaudio frame, retrieving data from the audio frame and the data frame ofthe packet and reproducing the data for data communication.

Employing the radio communication system according to the presentinvention increases the communication speed of data communication, andachieves higher speed transmission of data for data communicationcompared to conventional radio communication systems.

Also, the functions realized by the above-described radio communicationsystem can be realized by the radio apparatus, the radio communicationmethod, the packet generation method, and the method for reproducingdata from a packet according to the present invention, using a similarconfiguration or method.

These and other objects, features and advantages of the presentinvention will become more apparent upon reading of the followingdetailed description along with the accompanied drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a configuration of a radio apparatusaccording to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a packet transmitted by aradio apparatus.

FIG. 3 is a diagram showing types of data to be inserted in frames ofthe data part of a packet.

FIG. 4 is a diagram showing an arrangement of radio apparatuses andrepeaters in a radio communication system according to an embodiment ofthe present invention.

FIG. 5 is a flowchart showing processing performed by a controller fromthe start to the end of a packet transmission in a fast data mode.

FIG. 6 is a diagram showing types of data to be inserted in a packet inthe mode.

FIG. 7 is a flowchart showing processing performed by the controller ofa radio apparatus that has received a packet.

DETAILED DESCRIPTION OF THE INVENTION

The following describes a radio communication system according to anembodiment of the present invention, with reference to the drawings.

Measures to Increase Communication Speed of Data Communication

First, a description is given of a measure adopted in the presentinvention to increase the communication speed of data communication. Thepresent invention increases the communication speed of datacommunication by inserting data to be transmitted in data communicationinto audio frames used for transmitting audio signal data

In the following description, the communication mode in which audiosignal data is inserted into audio frames is referred to as “slow datamode”, and the communication mode in which data for data communicationis inserted into audio frames is referred to as “fast data mode”, basedon the difference in communication speed of the data communication.

When a transmission is performed in the fast data mode, which isselected from the above-described two communication modes, the receiverdoes not reproduce a sound and becomes silent. Therefore, if a devicefor displaying the communication data is not connected to the radioapparatus, there will be no way to distinguish between communication inthe fast data mode and silent communication.

Furthermore, when a conventional radio apparatus that does not supportthe fast data mode receives a fast data mode packet, the radio apparatuscannot reproduce the data for data communication from the packet, andaccordingly the user may misidentify the communication as silentinterferential communication.

For this reason, according to the present invention, the radio apparatusthat has received radio signals in the fast data mode is caused tooutput a beep sound at constant intervals, from its speaker, in order tonotify the user that communication is performed in the fast data mode.

Therefore, the user of the radio apparatus (the communication partystation) that has received radio signals can easily recognize thatcommunication is performed in the fast data mode, from the beep soundsthat are output periodically. This effect is beneficial particularlywhen a radio apparatus not supporting the fast data mode receives radiosignals.

Configuration of Radio Apparatus

Next, with reference to FIG. 1, a description is given of a radioapparatus used in a radio communication system according to the presentembodiment. A radio apparatus 1 includes a microphone 11, a speaker 12,an AF amplification unit 13, an audio codec 14, a transmission unit 15,a transmission/reception switching unit 16, an antenna 17, a receptionunit 18, an interface unit 19, a controller 21, an operation unit 26,and a display unit 28. In the drawing, thick arrows indicate the flow ofan audio signal, data, etc., and thin arrows indicate the flow of acontrol system signal.

The microphone 11 generates an analogue audio signal from an audioinput, and outputs the audio signal to the AF amplification unit 13. Thespeaker 12 converts an analogue audio signal output from the AFamplification unit 13, to a sound.

The AF (Audio Frequency) amplification unit 13 amplifies an analogueaudio signal input from the microphone 11, and supplies the resultantsignal to the audio codec 14. The AF amplification unit 13 alsoamplifies an analogue audio signal of a reception sound supplied fromthe audio codec 14, and outputs the resultant signal to the speaker 12.

The audio codec 14 performs an A/D (analogue/digital) conversion andencoding on an analogue audio signal supplied from the AF amplificationunit 13, and outputs the resultant signal to the transmission unit 15.The audio codec 14 also decodes, and furthermore performs a D/A(digital/analogue) conversion on, a digital audio signal supplied fromthe reception unit 18, and outputs the resultant signal to the AFamplification unit 13.

The transmission unit 15 adds a header for radio communication to adigital audio signal supplied from the audio codec 14, and alsogenerates a packet for transmission as shown in FIG. 2, based on anoutput from a PTT switch 27 described later. The configuration of thepacket will be described later in detail, with reference to FIG. 2. Thetransmission unit 15 furthermore modulates a carrier wave by usingdigital data contained in the packet, and transmits the resultant wavefrom the antenna 17 via the transmission/reception switching unit 16.

The transmission/reception switching unit 16 delivers the transmissionsignal from the transmission unit 15 to the antenna 17 when the PTTswitch 27 is pressed and turned ON, and delivers the reception signal ofthe antenna 17 to the reception unit 18 when the PTT switch 27 isreleased and turned OFF.

The reception unit 18 changes the reception frequency according to aninstruction signal from the controller 21, amplifies the receptionsignal obtained by tuning to the reception frequency, and furthermore,demodulates the resulting signal to reproduce a packet. Then, thereception unit 18 removes the header part from the reproduced packet,and supplies the audio data to the audio codec 14 and supplies the otherdata (e.g., packet data of an image signal, etc.) to the interface unit19.

The interface unit 19 is connected to an external device 31 (e.g., apersonal computer or a smartphone) via an external connection terminal20 and to a device 32 (e.g., a GPS receiver) that is built into theradio apparatus, and supplies packet data supplied from the externaldevice 31 and the built-in device 32, such as an image signal, to thetransmission unit 15 and the controller 21. The interface unit 19 alsosupplies packet data supplied from the reception unit 18, to theexternal device via the external connection terminal 20.

The controller 21 controls the operation of the radio apparatus 1. Thecontroller 21 includes a CPU (Central Processing Unit) 22, a ROM (ReadOnly Memory) 23 storing a program operating on the CPU 22, a RAM (RandomAccess Memory) 24 serving as a work memory for the CPU 22, and anon-volatile memory 25 storing data such as a call sign.

The operation unit 26 conveys various sorts of inputs and userinstructions to the controller 21. The operation unit 26 includes thePTT (Push To Talk) switch 27 and a mode switch 33 that is for switchingbetween communication modes. When the PTT switch 27 is pressed (turnedON), the transmission/reception switching unit 16 switches to thetransmission mode and a transmission from the antenna 17 is performed,and when the PTT switch 27 is released (turned OFF), thetransmission/reception switching unit 16 switches to the reception modeand the reproduction of the received audio signal is performed.

The display unit 28 includes a liquid crystal display or the like, andis used for displaying various sorts of data. The screen of the displayunit 28 displays, for example, information indicating that the radioapparatus 1 has received amateur radio signals (there has been a call),and call signs or nicknames of the transmission source (the user's ownstation) and the transmission destination (the communication partystation).

The radio apparatus 1 according to the present embodiment is alsoequipped with an audio encoder 29 for generating a beep sound,separately from the above-described general-purpose components. Theaudio encoder 29 generates coded data of a beep sound for notificationto the user, and generates a beep sound according to an instruction fromthe controller 21, and transmits the data of the beep sound to thetransmission unit 15.

Configuration of Packet

Next, with reference to FIG. 2 and FIG. 3, a description is given of theconfiguration of a packet generated by the transmission unit 15. Theconfiguration of the packet shows the order and the grouping of a seriesof data pieces to be transmitted in digital audio communication.

As shown in FIG. 2, a packet Pa includes a header part Ph and a datapart Pd. The header part Ph includes a synchronization signal h1, a flagh2, a transmission destination repeater call sign h3, a transmissionsource repeater call sign h4, a transmission destination call sign h5,and a transmission source call sign h6.

The synchronization signal h1 in the header part Ph is used forsynchronization with the reception signal, and indicates the startingpoint of the signal. The flag h2 is data for indicating communicationvia a repeater, direct communication, a repeater control signal, etc.,and is composed of a plurality of bits.

The transmission destination repeater call sign h3 is, for example, thecall sign of a repeater station within the repeater area to which thetransmission destination radio station belongs, and the transmissionsource repeater call sign h4 is a call sign of a repeater station withinthe repeater area to which the transmission source radio stationbelongs. The transmission destination call sign h5 is the call sign ofthe communication party station at the destination of the transmission,and the transmission source call sign h6 is the call sign of the user'sown station. These call signs (h3 to h6) serve as identifiers foridentifying the radio stations at the transmission destination and thetransmission source, as well as the repeater stations that relay theradio signals. Note that the transmission destination call sign h5 maybe CQ for making a call without the designation of any particularstation.

In order to achieve the simultaneous transmission of data for audiocommunication and data for data communication, the data part Pd includesaudio frames d1 and data frames d2, which are arranged one after theother, and a clearing frame d3 is attached to the end. Each of the audioframes d1 has a predetermined length, and a digitized audio signal isinserted into it. Each of the data frames d2 has a predetermined length,and data sets for data communication such as an image signal and amessage are inserted into it. The clearing frame d3 indicates the end ofthe packet.

Note that the data frames d2 are periodically replaced with aresynchronization frame d4 (e.g. every 420 ms). A synchronization signalfor synchronization with the radio apparatus of the communication partystation is inserted into each resynchronization frame d4.

Next, with reference to FIG. 3, a description is given of data for datacommunication, which is to be inserted into the data frames d2. FIG. 3shows the types of data to be inserted into each frame of the data partPd. In this drawing, “audio” shows that audio signal data is inserted inthe frame, and “data” shows that data for data communication is insertedin the frame.

Regarding the audio frames d1 and the data frames d2 constituting thedata part Pd, the data amount of the audio frames d1 is set to begreater than the data mount of the data frames d2, because thetransmission of audio signal data is given a high priority. Usually, 9bytes of data is inserted into each of the audio frames d1, and 3 bytesof data is inserted into each of the data frames d2.

Furthermore, a mini-header d5, which includes the description of thedata type, etc., is inserted in the beginning of the data frame d2.However, if the mini-header d5 is provided in every data frame, theamount of data that can be inserted in the data frame will be smaller,and therefore one mini-header d5 is inserted in one data frame out ofevery two data frames.

Therefore, as shown in FIG. 3 at the lower level, when generating thepacket Pa, communication data for data communication is divided into5-byte portions, and 1-byte mini-header d5 is added to the beginning ofeach portion so as to compose a data block, and after that, the datablock is divided into 3-byte portions, and these portions arerespectively inserted into two adjacent data frames d2.

Then, information indicating the data type and the data length iswritten into each mini-header d5. The data length indicates the lengthof the effective data inserted in a single data block. For example,suppose the case of transmitting general-purpose data having a datalength of 13 bytes, such as image data. First, when the data to betransmitted is divided into 5-byte portions as described above, the datawill be divided into three portions, namely 5-byte portion, 5-byteportion, and 3-byte portion. Then, the mini-header d5 is added to thebeginning of each of these data portions. Here, if the informationindicating the general-purpose data such as image data is 0×3 forexample, the mini-header d5 added to each of the first and second datablocks is 0×35, and the mini-header d5 added to the third data block is0×33.

The controller 21 (see FIG. 1) retrieves, via the interface unit 19, thedata indicating the data type, etc., from the data for datacommunication transmitted from an external device (not shown in thedrawings) connected to the terminal 20, and stores the retrieved data tothe RAM 24. Also, when the transmission unit 15 generates packets fortransmission, the controller 21 reads the aforementioned data from theRAM 24 and transfers it to the transmission unit 15. In the transferreddata, the information indicating the data type is written into themini-header d5.

Meanwhile, when reproducing the data for data communication from thepackets Pa reproduced by the reception unit 18, the reverse of theaforementioned process is performed, i.e., based on the information inthe mini-header d5, a 5-byte communication data portion is retrievedfrom the data contained in two data frames d2, the data for datacommunication is reproduced by concatenating the 5-byte communicationdata portions with each other, and the data for data communication istransmitted to an external device via the interface unit 19.

Operations for Communication in Slow Data Mode

As described above, the radio apparatus according to the presentembodiment can perform communication in two modes, the slow data modeand the fast data mode. First, a description is given of the operationsfor communication in the slow data mode, with reference to FIG. 1 toFIG. 3.

The operation unit 26 has a mode switch 33 for switching between thecommunication modes, and the user can select either the slow data modeor the fast data mode by operating the switch 33. The slow data mode isselected when communication is performed with a conventional radioapparatus that has no option for a communication mode, or when no datafor data communication needs to be transmitted, for example. Note that,the mode switch 33 may be other than the switch. For example, switchingbetween the modes may be instructed from a menu screen displayed when amenu button or the like is pressed.

As a typical case where the slow data mode is used, the followingdescribes the case where a radio apparatus (the user's own station)within a given area makes a call to a radio station (the communicationparty station) within another area.

FIG. 4 shows an arrangement of radio apparatuses and repeaters in aradio communication system according to the present embodiment. A radiocommunication system 100 includes at least two radio apparatuses 1 andat least one repeater 3. In the example shown in FIG. 4, radioapparatuses 1 a, 1 b, and 1 c exist within an area 2 a covered by arepeater 3 a, and radio apparatuses 1 d and 1 e exist within an area 2 bcovered by a repeater 3 b. The adjacent repeaters 3 a and 3 b transmitaudio and data in a multiplexed state to each other by using microwaves.

The following describes a case in which the radio apparatus 1 a withinthe area 2 a and the radio apparatus 1 d within the area 2 b communicatewith each other. Before starting the communication, the user operatesthe operation unit 26 of the radio apparatus 1 a in order to store, tothe non-volatile memory 25, information necessary for the communication,such as the call sign of the transmission source (the user's ownstation) and the call signs of the repeater stations.

When starting the communication, the user operates the operation unit 26of the radio apparatus 1 a in order to make a call with the designationof the call sign given to the transmission destination radio station andthe call sign of the transmission destination repeater.

When the user presses the PTT switch 27, the information input from theoperation unit 26 is provided to the transmission unit 15 by thecontroller 21, and the transmission unit 15 generates a packet accordingto an instruction form the controller 21. As shown in FIG. 2, the headerpart Ph of the packet Pa contains the call sign h3 of the transmissiondestination repeater, the call sign h4 of the transmission sourcerepeater, the call sign h5 of the transmission destination (thecommunication party station), and the call sign h6 of the transmissionsource (the user's own station).

Within the data part Pd of the packet Pa, audio signal data output fromthe audio codec 14 is inserted into the audio frames d1, and data fordata communication transferred from the interface unit 19 is insertedinto the data frames d2.

The packet Pa generated and converted into radio signals by thetransmission unit 15 are transmitted via the transmission/receptionswitching unit 16 and the antenna 17. The packet Pa transmitted by theradio apparatus 1 a (the user's own station) is relayed by the repeaters3 a and 3 b, and reaches the radio apparatus 1 d (the communicationparty station).

The radio signals received by the radio apparatus 1 d (the communicationparty station) are provided to the reception unit 18 via the antenna 17and the transmission/reception switching unit 16, and are demodulated bythe reception unit 18, and thus the packet Pa is reproduced.Furthermore, the header part Ph is removed from the packet Pa reproducedby the reception unit 18, and the data part Pd is provided to the audiocodec 14 or the interface unit 19, depending on the contents of the datapart Pd.

Audio signal data provided to the audio codec 14 is decoded, and isfurthermore converted into an analogue audio signal, and is thenprovided to the AF amplification unit 13. The audio signal amplified bythe AF amplification unit 13 is output from the speaker 12, and thus thevoice of the user of the transmission source is reproduced.

In contrast, the data for data communication obtained by demodulatingthe packet shown in FIG. 3 is transferred to the external device 31 viathe interface unit 19.

Furthermore, the packet Pa reproduced by the reception unit 18 isprovided to the controller 21. The CPU 22 of the controller 21determines whether or not the packet Pa thus received is a valid packet,by performing ECC (Error Check Code) check, etc.

The CPU 22 stores, to the RAM 24, the data in the header part Ph of thepacket Pa determined to be valid, and also analyzes the information inthe header part Ph. According to the results of the analysis, the CPU 22displays, on the display unit 28, the transmission destination callsign, the transmission source call sign, etc. of the received packet Pa.

Operations for Communication in Fast Data Mode

Next, with reference to FIG. 5, FIG. 6, and FIGS. 1 to 3 describedabove, a description is given of the operations for communication in thefast data mode. As described above, in the radio communication systemaccording to the present embodiment, the radio apparatus 1 that hasreceived radio signals is caused to output a beep sound at constantintervals from the speaker 12 in order to notify the user thatcommunication is performed in the fast data mode.

FIG. 5 is a flowchart for the process performed by the controller 21during the period from when the transmission of the packet Pa in thefast data mode is started to when it is stopped. FIG. 6 shows types ofdata to be inserted into the packet Pa generated by the transmissionunit 15 during the same period.

Note that the descriptions of the operations that the user performsbefore starting the communication, such as the operation for storing theinformation necessary for the communication to the non-volatile memory25, the operation for designating the transmission destination call signand the call sign of the transmission destination repeater, and so onare omitted, because they are the same as in the communication performedin the slow data mode.

There are two methods for switching to the fast data mode. The firstmethod is the method by which the user switches the mode to the fastdata mode by operating the mode switch 33 of the aforementionedoperation unit 26. This method is used, for example, in the case oftransmitting data for data communication accumulated in an externaldevice.

The second method is the method by which the controller 21 automaticallyswitches the mode to the fast data mode when the controller 21 detectsthat data for data communication is transmitted from the external device31 or the built-in device 32 to the interface unit 19 under thecondition where the user is not pressing the PTT switch 27, i.e., theuser is not making an instruction to transmit an audio signal.

Regardless of which method is employed, the controller 21 transmits, tothe transmission unit 15, a command for starting a transmission in thefast data mode (Step S1).

Upon receiving from the controller 21 the command for starting thetransmission, the transmission unit 15 starts generating the packet Pa.Specifically, as shown in FIG. 6, the transmission unit 15 generates apacket in which data for data communication is inserted in each of theaudio frames d1 and data frames d2. The packet Pa thus generated isfurthermore converted into high-frequency signals by the transmissionunit 15, and they are transmitted from the antenna 17, as radio signals.

Note that when the fast data mode is selected by the second method,carrier sensing, which is for determining whether or not thetransmission channel is used by any other stations, is performed beforetransmitting radio signals, in order to prevent the radio signals fromcolliding with other radio signals.

As described above with reference to FIG. 3, when an audio communicationand a data communication are simultaneously performed in the slow datamode, i.e., the communication mode in which audio signal data isinserted into audio frames, 9 bytes of audio signal data is insertedinto each audio frame d1. Meanwhile, regarding data for datacommunication, a data block composed of a communication data portion d6,which is one of the divided 5-byte portions, and the mini-header d5added to the beginning of the communication data portion d6, is dividedinto two portions, and these two portions are respectively inserted intotwo data frames d2.

In contrast, in the case of using both the audio frames and the dataframes to transmit data for data commination in the fast data mode,i.e., the mode in which data for data communication is inserted intoaudio frames, the data to be transmitted is divided into 20-byteportions, and the mini-header d5 and so on is added to each portion soas to compose a block, and the data of the block is divided and insertedinto two adjacent audio frames d1 and two adjacent data frames d2.

Specifically, each block is 24-byte data composed of 20-byte data fordata communication, a 1-byte mini-header, 2-byte unique data to beinserted in each audio frame for abnormal noise reduction, and 1-bytedate to be inserted into data frames in order to prevent themisdetection of packet loss, and this data block is divided and insertedinto two adjacent audio frames d1 (9 bytes×2) and two adjacent dataframes d2 (3 bytes×2).

If a comparison is made between the case of inserting the audio signaldata into the audio frames d1 of the packet Pa and the case of insertingthe data for data communication into the audio frames d1, thecommunication speed of the latter case is approximately 3.5 times thecommunication speed of the former case, and the data for datacommunication can be transmitted at high speed in the latter case.

The following is a continuation of the description of FIG. 5. When afirst time period T1 has elapsed since the controller 21 transmitted thecommand for starting the communication (Yes in Step S2), the controller21 transmits to the audio encoder 29 a command for generating coded dataof a beep sound, and furthermore, transmits to the transmission unit 15a command for inserting the coded data of a beep sound into the audioframes d1 (Step S3). Here, the first time period T1 indicates the periodof the cycle of beep sounds.

Upon receiving from the controller 21 the command for inserting a beepsound, the transmission unit 15, as shown in FIG. 6, waits until thebreakpoint of the block of the data for data communication, and theninserts the data of a beep sound output from the audio encoder 29, intothe audio frames d1.

When a second time period T2 shorter than the first time period T1 haselapsed after the controller 21 transmitted, to the transmission unit15, the command for inserting a beep sound (Yes in Step S4), thecontroller 21 transmits to the transmission unit 15 a command forreturning to the fast data mode, and also transmits to the audio encoder29 a command for stopping the generation of a beep sound (Step S5).Here, the second time period T2 indicates the period during which beepsounds are emitted.

Hereafter, returning to the original mode, the transmission unit 15generates a packet in which data for data communication is inserted ineach of the audio frames d1 and data frames d2.

Subsequently, the controller 21 checks the reception status of the datafor data communication received by the interface unit 19 (Step S6), andwhen the data reception is still continuing (No in Step S6), the processreturns to Step S2, and the controller 21 repeatedly transmits thecommand for inserting the coded data of a beep sound to the transmissionunit 15, and the command for generating the coded data of a beep soundto the audio encoder 29, at intervals of the first time period T1.

On the other hand, when the reception of the data for data communicationby the interface unit 19 is interrupted at the end of the data (Yes inStep S6), the controller 21 transmits to the transmission unit 15 acommand for stopping the transmission (Step S7). Upon receiving thecommand for stopping the transmission, the transmission unit 15 insertsthe clearing frame d3 into the packet Pa as shown in FIG. 6, and stopsthe generation and transmission of packets.

Although not shown in the flowchart in FIG. 5, when the user presses thePTT switch 27 during a communication in the fast data mode, the priorityis given to the operation of the PTT switch 27, and the controller 21detects the signal from the operation unit 26 and switches thecommunication mode to the slow data mode.

Specifically, the controller 21 transmits to the transmission unit 15 acommand for starting a transmission in the slow data mode, i.e., acommand for inserting digital audio signals into the audio frames d1.

Upon receiving this command, the transmission unit 15 waits until thebreakpoint of the block of the data for data communication, and insertsthe digital audio signals supplied from the audio codec 14, into theaudio frames d1. As a matter of course, no beep sound is inserted intothe packet Pa in the slow data mode.

Next, a description is given of a data reproduction method for a radioapparatus (the communication party station) that has received radiosignals generated according to the procedure shown in FIG. 5 andtransmitted by a radio apparatus (the user's own station). Thecontroller 21 performs the process of reception data reproductionaccording to the flowchart shown in FIG. 7.

The controller 21 retrieves the data in the data frames d2 from the dataof the packet Pa, which has been reproduced by the reception unit 18from the radio signals, and then writes it into a built-in register (notshown in the drawing) (Step S11). The controller 21 analyzes theinformation in the mini-header d5, and determines whether or not thepacket Pa is a packet transmitted in the fast data mode (Step S12).

As shown in FIG. 6, in a communication in the fast data mode, data fordata communication is inserted in the beginning of the data part Pd ofthe packet Pa and in the audio frames d1 after the second time period T2has elapsed within the first time period T1.

When determining that the data for data communication is inserted in theaudio frames d1 (Yes in Step S13), the controller 21 instructs thereception unit 18 to retrieve the data for data communication (8 bytesin the present embodiment) from the audio frames d1, while excludingdata for abnormal noise reduction (1 byte in the present embodiment)from the audio frames d1 (Step S14).

Next, the controller 21 concatenates the data portions retrieved fromtwo adjacent audio frames d1 and two adjacent data frames d2 in reverseorder to how the block is created as described above, therebyreproducing the data for data communication (Step S15). The data fordata communication thus reproduced is output to the interface unit 19.

The controller 21 instructs the interface unit 19 to transfer thereproduced data for data communication to the external device (StepS16), and the interface unit 19 outputs the reproduced data for datacommunication to the external device according to the instruction. Inthis way, the data for data communication is transmitted with increasedspeed to the external device.

Meanwhile, as shown in FIG. 6, the audio signal of a beep sound has beeninserted in each audio frame d1 of the packet Pa until the end of thesecond time period T2 within the first time period T1. When determiningthat the beep sound data is inserted in the audio frames d1 (No in StepS13), the controller 21 instructs the reception unit 18 to retrieve thebeep sound data (9 bytes in this embodiment) contained in the audioframes d1 (Step S17).

Next, the controller 21 instructs the audio codec 14 to decode the beepsound data retrieved from the reception unit 18 (Step S18), and theaudio codec 14 performs beep sound decoding according to the instructionfrom the controller 21. The beep sound decoded and converted into ananalogue audio signal is output from the speaker 12.

Therefore, the user of the radio apparatus 1 (communication partystation) that has received the radio signals can easily recognize thatcommunication is performed in the fast data mode, from the sequences ofbeep sounds that are output in cycles of the first time period T1. Thiseffect is beneficial particularly when a radio apparatus that does notsupport the fast data mode receives radio signals.

In parallel with Steps S17 and S18, the controller 21 concatenates thedata portions retrieved from the data frames d2 and stored in theregister, thereby reproducing the data for data communication (StepS19). The data for data communication thus reproduced is output to theinterface unit 19.

Next, the controller 21 performs the above-described Step S16, in otherwords instructs the interface unit 19 to transfer the reproduced datafor data communication to the external device 31, and the interface unit19 outputs the reproduced data for data communication to the externaldevice 31 according to the instruction.

In the above-described embodiment, it is preferable that the first timeperiod T1, which indicates the period of the cycle of beep sounds, isapproximately 1 second. Also, it is preferable that the second timeperiod T2, which is the period during which beep sounds are emitted, isapproximately 0.1 to 0.2 seconds, because the communication speeddecreases if the second time period T2 is too long, and on the otherhand it becomes hard to recognize the beep sounds if the second timeperiod T2 is too short.

In the above-described embodiment, the audio encoder 29 is used forgenerating the beep sound. However, the means for generating the beepsound is not limited to this. The audio signal data in itself of thebeep sound may be stored in the non-volatile memory 25, and thecontroller 21 may read the data and transmit it to the transmission unit15 during the second time period T2.

The following summarizes preferable examples of the embodiment of thepresent invention.

The data frame has a mini-header inserted therein, the mini-headercontaining information describing a data type, and the transmission unitwrites, in the mini-header, the information indicating that data fordata communication is inserted in the audio frame, as a portion of theinformation describing the data type.

In communication in the fast data mode, the transmission unit insertsnotification sound data into the audio frame according to an instructionfrom the controller, at intervals of a first time period.

The radio apparatus further includes an audio encoder configured togenerate coded notification sound data, and the audio encoder generatesthe coded notification sound data according to an instruction from thecontroller, and outputs the coded notification sound data to thetransmission unit during a second time period that is shorter than thefirst time period.

The radio apparatus further includes an operation unit configured toinput an instruction from a user to the controller, and even duringcommunication in the fast data mode, the controller, upon receiving fromthe user via the operation unit an instruction to transmit an audiosignal, instructs the transmission unit to switch to communication in aslow data mode that is a mode in which a digital audio signal to betransmitted is inserted into the audio frame.

In a situation where an instruction to transmit an audio signal is notinput to the operation unit by the user, the controller instructs thetransmission unit to perform communication in the fast data mode whenreceiving data for data communication from an external device or adevice that is built into the radio apparatus.

The operation unit is provided with a mode switch that allows forselection of either the slow data mode or the fast data mode.

Although the present invention has been fully described by way ofexample with reference to the accompanied drawings, it is to beunderstood that various changes and modifications will be apparent tothose skilled in the art.

Therefore, unless otherwise such changes and modifications from thescope of the present invention hereinafter defined, they should beconstrued as being included therein.

What is claimed is:
 1. A radio communication system including at leasttwo radio apparatuses, each radio apparatus comprising: a transmissionunit configured to generate a packet including: a header part containingidentifier data identifying at least a transmission destination radiostation and a transmission source radio station; and a data part inwhich an audio frame and a data frame, each having a predeterminedlength, are consecutively arranged one after another, to insert audiosignal data into the audio frame of the packet and to insert data otherthan the audio signal data into the data frame of the packet, and tothereafter convert the packet into a radio signal and transmit the radiosignal; a reception unit configured to receive the radio signal, toreproduce a packet from the radio signal, to retrieve the audio signaldata from the audio frame of the packet, and to retrieve the data otherthan the audio signal data from the data frame of the packet; an audiocodec configured to generate a digital audio signal by performing A/Dconversion and encoding on an analogue audio signal and thereaftertransmit the digital audio signal to the transmission unit, and toreproduce an analogue audio signal by performing decoding and D/Aconversion on a digital audio signal received from the reception unit;and a controller configured to instruct the transmission unit togenerate a packet, and to instruct the reception unit to reproduce apacket from a received radio signal, wherein, when communication isperformed in a fast data mode in which data for data communication to betransmitted, instead of audio signal data, is inserted in the audioframe, the transmission unit of a radio apparatus serving as a sendergenerates, according to an instruction from the controller, a packet inwhich data for data communication is inserted in the audio frame and thedata frame, and information indicating that the data for datacommunication is inserted in the audio frame is further inserted in apredetermined position in the data frame, and the controller of a radioapparatus serving as a recipient, which has received a radio signal,analyzes the information inserted in the predetermined position in thedata frame of the packet reproduced by the reception unit, to determinethat the data for data communication is inserted in the audio frame, andaccording to a result of the determination, retrieves data from theaudio frame and the data frame of the packet and reproduces the data fordata communication.
 2. The radio communication system according to claim1, wherein the data frame has a mini-header inserted therein, themini-header containing information describing a data type, and thetransmission unit writes, in the mini-header, the information indicatingthat data for data communication is inserted in the audio frame, as aportion of the information describing the data type.
 3. The radiocommunication system according to claim 1, wherein, in communication inthe fast data mode, the transmission unit inserts notification sounddata into the audio frame according to an instruction from thecontroller, at intervals of a first time period.
 4. The radiocommunication system according to claim 3, wherein the radio apparatusfurther comprises an audio encoder configured to generate codednotification sound data, and the audio encoder generates the codednotification sound data according to an instruction from the controller,and outputs the coded notification sound data to the transmission unitduring a second time period that is shorter than the first time period.5. The radio communication system according to claim 1, wherein theradio apparatus further comprises an operation unit configured to inputan instruction from a user to the controller, and even duringcommunication in the fast data mode, the controller, upon receiving fromthe user via the operation unit an instruction to transmit an audiosignal, instructs the transmission unit to switch to communication in aslow data mode that is a mode in which a digital audio signal to betransmitted is inserted into the audio frame.
 6. The radio communicationsystem according to claim 5, wherein, in a situation where aninstruction to transmit an audio signal is not input to the operationunit by the user, the controller instructs the transmission unit toperform communication in the fast data mode when receiving data for datacommunication from an external device or from a device that is built inthe radio apparatus.
 7. The radio communication system according toclaim 5, wherein the operation unit is provided with a mode switch thatallows for selection of either the slow data mode or the fast data mode.8. A radio apparatus comprising: a transmission unit configured togenerate a packet including: a header part containing identifier dataidentifying at least a transmission destination radio station and atransmission source radio station; and a data part in which an audioframe and a data frame, each having a predetermined length, areconsecutively arranged one after another, to insert audio signal datainto the audio frame of the packet and to insert data other than theaudio signal data into the data frame of the packet, and to thereafterconvert the packet into a radio signal and transmit the radio signal; anaudio codec configured to generate a digital audio signal by performingA/D conversion and encoding on an analogue audio signal and thereaftertransmit the digital audio signal to the transmission unit; and acontroller configured to instruct the transmission unit to generate apacket, wherein, when communication is performed in a fast data mode inwhich data for data communication to be transmitted, instead of audiosignal data, is inserted in the audio frame, the transmission unitgenerates, according to an instruction from the controller, a packet inwhich data for data communication is inserted in the audio frame and thedata frame, and information indicating that the data for datacommunication is inserted in a predetermined position in the audio frameis further inserted in the data frame.
 9. The radio apparatus accordingto claim 8, wherein the data frame has a mini-header inserted therein,the mini-header containing information describing a data type, and thetransmission unit writes, in the mini-header, the information indicatingthat data for data communication is inserted in the audio frame, as aportion of the information describing the data type.
 10. The radioapparatus according to claim 8, wherein, in communication in the fastdata mode, the transmission unit inserts notification sound data intothe audio frame according to an instruction from the controller, atintervals of a first time period.
 11. The radio apparatus according toclaim 10, further comprising an audio encoder configured to generatecoded notification sound data, wherein the audio encoder generates thecoded notification sound data according to an instruction from thecontroller, and outputs the coded notification sound data to thetransmission unit during a second time period that is shorter than thefirst time period.
 12. The radio apparatus according to claim 8, furthercomprising an operation unit configured to input an instruction from auser to the controller, wherein, even during communication in the fastdata mode, the controller, upon receiving from the user via theoperation unit an instruction to transmit an audio signal, instructs thetransmission unit to switch to communication in a slow data mode that isa mode in which a digital audio signal to be transmitted is insertedinto the audio frame.
 13. The radio apparatus according to claim 12,wherein, in a situation where an instruction to transmit an audio signalis not input to the operation unit by the user, the controller instructsthe transmission unit to perform communication in the fast data modewhen receiving data for data communication from an external device orfrom a device that is built in the radio apparatus.
 14. The radioapparatus according to claim 12, wherein the operation unit is providedwith a mode switch that allows for selection of either the slow datamode or the fast data mode.
 15. The radio apparatus according to claim8, further comprising a reception unit configured to receive the radiosignal, to reproduce the packet from the received radio signal, toretrieve audio signal data from the audio frame of the packet, and toretrieve data other than the audio signal data from the data frame,wherein, when a radio signal transmitted in the fast data mode isreceived, the controller analyzes the information inserted in apredetermined position in the data frame of the packet reproduced by thereception unit, to determine that data for data communication isinserted in the audio frame, and according to a result of thedetermination, retrieves data from the audio frame and the data frame ofthe packet and reproduces the data for data communication.
 16. A radiocommunication method for a radio communication system including at leasttwo radio apparatuses, one of the at least two radio apparatuses beingconfigured to generate a packet including: a header part containingidentifier data identifying at least a transmission destination radiostation and a transmission source radio station; and a data part inwhich an audio frame and a data frame, each having a predeterminedlength, are consecutively arranged one after another, and to convert thepacket into a radio signal and transmit the radio signal, and anotherone of the at least two radio apparatuses being configured to receivethe radio signal and reproduce a packet from the received radio signal,the radio communication method comprising the steps of: with a radioapparatus serving as a sender, generating a packet in which data fordata communication is inserted in the audio frame and the data frame,and information indicating that the data for data communication isinserted in the audio frame is inserted in the data frame; andconverting the generated packet into a radio signal and transmitting theradio signal, and with a radio apparatus serving as a recipient,receiving the radio signal; reproducing a packet from the received radiosignal; analyzing information that is inserted in the data frame of thereproduced packet to determine whether or not data for datacommunication is inserted in the audio frame; and when determining thatthe data for data communication is inserted in the audio frame,retrieving data from the audio frame and the data frame of the packetand reproducing the data for data communication.
 17. The radiocommunication method according to claim 16, further comprising the stepsof: with the radio apparatus serving as a sender, inserting notificationsound data into the audio frame at intervals of a first time period andgenerating a packet, and with the radio apparatus serving as arecipient, reproducing a packet, retrieving notification sound data fromthe audio frame of the reproduced packet, converting the notificationsound data into an analogue audio signal, and outputting the analogueaudio signal from a speaker.
 18. A packet generation method for a radioapparatus that performs communication with another radio apparatus byusing a packet that includes: a header part containing identifier dataidentifying at least a transmission destination radio station and atransmission source radio station; and a data part in which an audioframe and a data frame, each having a predetermined length, areconsecutively arranged one after another, the packet generation methodcomprising the steps of: inserting data for data communication into theaudio frame and the data frame; and inserting, into the data frame,information indicating that the data for data communication is insertedin the audio frame.
 19. The packet generation method according to claim18, further comprising the step of inserting notification sound datainto the audio frame at intervals of a first time period.
 20. A methodfor reproducing data from a packet performed by a radio apparatus thatis configured to receive a radio signal containing a packet generated bythe packet generation method according to claim 18, and to reproduce thepacket from the radio signal, the method comprising the steps of:analyzing information that is inserted in the data frame of thereproduced packet to determine whether or not data for datacommunication is inserted in the audio frame; and when determining thatthe data for data communication is inserted in the audio frame,retrieving data from the audio frame and the data frame of the packetand reproducing the data for data communication.